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S S Nikol'skiĭ

Publications and source records attributed to S S Nikol'skiĭ.

3 recordsLinked to original sources
PubMedDate not supplied

[Thermodynamics and muscle contraction. II. Consequences of the principle of maximization of the rate of entropy production].

For non-elastic irreversible mechanochemical machines of the muscular type, the above-mentioned principle (by H. Ziegler) leads to the following results. The velocity of shortening, v, decreases when the force F increases. The mechanical power of the system Fv, is active when 0 greater than v greater than vF=0 or 0 greater than F greater than Fv=0. At F=0 the rate of chemical reaction has the maximum and dQ/dF = -v greater than 0 (where Q is the rate of heat production). At v = 0 the rate of entropy production has the minimum and d/dv = F/A greater than 0 (where A is an affinity of the chemical reaction). The Onsager symmetry relation holds at v=0 only.

Mathematics↗
PubMedDate not supplied

[Autoregulated mechanochemical models].

Systems are analysed which consists of connected in parallel or series contractile (reactor-Rc) and elastic (elastic body-EB) parts similar to Kelvin or Maxwell's rheological models and to sarcomeres of the insect flying muscle (IFM) or vertebrate skeletal muscle. The feedback takes place if EB is a deformable sorbent of the mobile activator or inhibitor (effector--E) of the mechanochemical process proceeding in Rc. The condition of oscillative instability of mechanical rest was found for the system of the parallel type. This condition requires that E migration in the system Rc--EB braught about contraction (lengthening) of EB simultaneously with an increase (weakening) of the stretching force on EB from Rc. The oscillation frequency nu satisfies approximate ratio nu approximately less than DL-2 (where D--E diffusion coefficient, L--typical distance between Rc and EB), corresponding to specific frequencies in IFM. An automatic correction of the process in Rc is possible for the system of the serial type in order to increase useful mechanical power. Such a correction is achieved when a series elastic component contracts while absorbing E, if E is the process activator in Rc.

Animals↗